A grapple is generally a well known type of work tool that is often attached to machinery, such as excavators, backhoes etc. Applications of a grapple include material gripping, handling, or cutting capability. Used with an excavator, this gripping and handling capability makes the excavator suitable for a variety of operations. For example, excavators employing grapple assemblies are often used in demolition (e.g, tearing down lightweight structures made of wood or brick, or sorting, picking, placing, and loading materials, or cutting materials if needed).
Typically grapples include two gripping members (sometimes referred to as blades or cutting edges) that are attachable to the grapple, and when brought together, grip the desired material. That is, the grapple has a shell, and these gripping members are each associated with one portion of the shell, such that as the shell is closed, the gripping members grip the material.
For new gripping members, if no material was involved and the shells were closed, the gripping members would contact each other on a gripping edge of the gripping member. As the gripping members wear, and more particularly, as the gripping edge of these members wear, an overbite forms between the members when they are brought together. For example, one gripping edge will go over the other gripping edge, instead of having the edges come together. This overbite can cause inefficiencies in gripping and cutting material.
There are some grapple implementations that use mechanical end stops to control the distance a grapple shell travels. When the gripping members are new, the mechanical end stops aid in stopping the travel of the shell when the gripping edges come together. However, as the gripping edges wear, the mechanical stops, stop the shells at approximately the same range of travel, resulting in a gap between the gripping edges. Again, this gap can cause inefficiencies in gripping and cutting material. Even if the mechanical end stops allowed the grapple shells to travel further to account for the gap, the result would still be an overbite between the two gripping surfaces as shown in FIG. 6.
The present invention is directed to overcome or improve one or more disadvantages associated with the prior methods and apparatus.